The present invention relates to a conveyance roller of a photosensitive material processing apparatus. Also, the present invention relates to a photosensitive material processing apparatus in which the conveyance roller is used.
Concerning the structure of the photosensitive material conveyance means, a conveyance system in which a pair of rollers come into pressure contact with each other is mainly used. According to this system, in order to provide a conveyance force at one position, it is necessary to arrange a pair of rollers, that is, it is necessary to arrange two rollers. When sheets of photographic paper are conveyed, for example, sheets of color photographic paper are conveyed, it is necessary to provide pairs of conveyance rollers, the intervals of which are not more than the minimum sheet width. In this case, a large number of relatively expensive conveyance rollers are used, so that the costs are raised. Since a space corresponding to two pairs of rollers are required for one rack, the dimensions of the apparatus are increased.
Recently, in an automatic developing apparatus, which is an apparatus for processing photosensitive material, the processing time required for developing, bleaching, fixing and stabilizing is remarkably shortened. Accordingly, length of the rack in each processing tank is reduced. Further, technique of processing photosensitive material without washing has made rapid progress in recent years. Due to the foregoing, the automatic developing apparatus is made to be more compact and the prices is further reduced. For this reason, in a mini-laboratory for processing color photosensitive material in a retail shop, there is a strong demand for reduction of the size of the automatic developing apparatus so that the automatic developing apparatus can be installed in a small space, and also there is a strong demand for reduction of the cost.
The present invention has been accomplished to solve the above problems. The first object of the present invention is to provide a compact photosensitive material processing apparatus having a simple photosensitive material conveyance structure capable of processing photosensitive material of high quality at low cost without deteriorating the ability and performance of processing photosensitive material.
Conventionally, a hard resin roller, the core member of which is composed of a stainless steel pipe and covered with a layer of hard resin such as hard vinyl chloride or phenol resin, is used for a conveyance roller arranged in the processing solution tank of a photosensitive material processing apparatus. Also, a rubber roller, the core member of which is composed of a stainless steel pipe and covered with a layer of silicon rubber or ethylene-propylene rubber, is used for the conveyance roller. The reason is that the costs of the above rollers are low and the chemical resistance is high.
As the processing speed of photosensitive material has been increased recently, it is desired to increase the conveyance speed of photosensitive material in the processing tank. However, when the conveyance speed of photosensitive material is increased, the conveyance rollers described above are disadvantageous in that slippage of photosensitive material tends to occur and further the photosensitive material skews while it is conveyed. Therefore, it is difficult to provide a stable conveyance performance.
A method to solve the above problems at low cost is disclosed in Japanese Utility Model Publication Open to Public Inspection No. 44640/1992, in which fine particles are diffused in the material of a plastic roller, and the material is subjected to extrusion so that the outer circumferential surface of the roller can be made to be rough.
Even when the above improved roller is used, it is impossible to avoid the slippage and skew of photosensitive material in the processing solution tank in the process of high speed conveyance of photosensitive material, and it is difficult to convey the photosensitive material at high speed under a stable condition.
However, the above system has several disadvantages which will be described below: When the photosensitive material is conveyed, the sheet of photosensitive material is pressed by the rotating conveyance roller. Therefore, end portions of the sheet of photosensitive material are also stained in such a manner that the end portions of photosensitive material are stained with the solution, and the formed image becomes uneven.
The present invention has been accomplished to solve the above problems. The second object of the present invention is to provide a conveyance roller by which the occurrence of slippage and skew of photosensitive material can be prevented even when the photosensitive material is conveyed at high speed in a photosensitive material processing tank.
In this photosensitive processing apparatus, even when a sheet of photosensitive material is pressed by the conveyance rollers, end portions of the sheet are prevented from contamination.